Check out his other stuff too. You have to dig a little, and the site is all Japanese, but it's worth it. For example his mostly scratchbuilt Robotmasters Soundwave is a stunning example of what Titanium Soundwave should have been!

Should be easy enough, to do that Scratchbuild for Mixmaster, I have never done anything like that myself before, but that above mentioned site, his customs look like they are done without, they look flawless.